the cs(7p)+h/sub 2/ to csh+h reaction is studied in a crossed-beam experiment with laser-induced fluorescence detection of csh products. the usual flux ( approximately=50 mw/mm/sup 2/) which is delivered by the c.w. tunable dye laser used in the experiment is enough to saturate the absorption by csh products. then, by crossing twice the laser beam through the collision volume (counterpropagating beams), one realizes the conditions of saturated-absorption experiments' when the laser frequency is tuned to a resonance frequency of csh products, a defect to absorption occurs for these products which scatter in the collision plane and a 'saturation dip' appears at the center of the corresponding fluorescence profile. application of this technique to crossed-beam experiments can lead to the selection of product molecules which scatter in any definite plane. a different geometry of the laser beam (bent beams) is proposed to select molecules which scatter in any definite direction' it could be applied to detect an asymmetry in the scattering of the products with respect to the collision axis, when a particular preparation of the reagents is realized